DESCRIPTION: (Verbatim from the Applicant's Abstract) Spatial neglect impairs a person's ability to interact with their environment. Many of the symptoms of neglect can be induced by unilateral hemispheric injections of neurotoxins that unilaterally impair the dopaminergic systems. However, on standard test of neglect most patients with Parkinson's disease (PD) do not demonstrate neglect. PD patients most often have bilateral dopamine dysfunction and the failure to find unilateral neglect in these patients may be related to the bilaterality of this disease. There have been several reports of patients with bilateral lesions who had neglect of near or far peripersonal space. To learn if patients with PD may be neglecting far peripersonal space, we performed a pilot study. In this study we attempted to learn if the perceived size of lines or amplitude of movements were influenced by the spatial location of the stimulus in respect to the body. We found that when PD subjects perceived lines close to their body (medial) and tired to move an equal distance laterally they were hypometric. However, when they prceived a line laterally and movements centrally (medial) they were hypometric. These results suggested to us that patietns with PD may have either an abnormal perception of space, an abnormal response pattern or both. The purpose of this program is to further study Parkinson's patients spatial perceptions ad motor action sot learn if far peripersonal space is represented differently than near peripersonal space